[PATCH 2/2] tracing: Use switch statement instead of ifs in set_tracer_flag()

[Steven Rostedt]

From: Steven Rostedt <rost...@goodmis.org>

The "mask" passed in to set_trace_flag() has a single bit set. The
function then checks if the mask is equal to one of the option masks and
performs the appropriate function associated to that option.

Instead of having a bunch of "if ()" statement, use a "switch ()"
statement instead to make it cleaner and a bit more optimal.

No function changes.

Signed-off-by: Steven Rostedt (Google) <rost...@goodmis.org>
---
 kernel/trace/trace.c | 38 +++++++++++++++++++++++---------------
 1 file changed, 23 insertions(+), 15 deletions(-)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 07bd10808277..8460bec9f263 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -5251,11 +5251,13 @@ int trace_keep_overwrite(struct tracer *tracer, u64 
mask, int set)
 
 int set_tracer_flag(struct trace_array *tr, u64 mask, int enabled)
 {
-       if ((mask == TRACE_ITER(RECORD_TGID)) ||
-           (mask == TRACE_ITER(RECORD_CMD)) ||
-           (mask == TRACE_ITER(TRACE_PRINTK)) ||
-           (mask == TRACE_ITER(COPY_MARKER)))
+       switch (mask) {
+       case TRACE_ITER(RECORD_TGID):
+       case TRACE_ITER(RECORD_CMD):
+       case TRACE_ITER(TRACE_PRINTK):
+       case TRACE_ITER(COPY_MARKER):
                lockdep_assert_held(&event_mutex);
+       }
 
        /* do nothing if flag is already set */
        if (!!(tr->trace_flags & mask) == !!enabled)
@@ -5266,7 +5268,8 @@ int set_tracer_flag(struct trace_array *tr, u64 mask, int 
enabled)
                if (tr->current_trace->flag_changed(tr, mask, !!enabled))
                        return -EINVAL;
 
-       if (mask == TRACE_ITER(TRACE_PRINTK)) {
+       switch (mask) {
+       case TRACE_ITER(TRACE_PRINTK):
                if (enabled) {
                        update_printk_trace(tr);
                } else {
@@ -5283,9 +5286,9 @@ int set_tracer_flag(struct trace_array *tr, u64 mask, int 
enabled)
                        if (printk_trace == tr)
                                update_printk_trace(&global_trace);
                }
-       }
+               break;
 
-       if (mask == TRACE_ITER(COPY_MARKER)) {
+       case TRACE_ITER(COPY_MARKER):
                update_marker_trace(tr, enabled);
                /* update_marker_trace updates the tr->trace_flags */
                return 0;
@@ -5296,10 +5299,12 @@ int set_tracer_flag(struct trace_array *tr, u64 mask, 
int enabled)
        else
                tr->trace_flags &= ~mask;
 
-       if (mask == TRACE_ITER(RECORD_CMD))
+       switch (mask) {
+       case TRACE_ITER(RECORD_CMD):
                trace_event_enable_cmd_record(enabled);
+               break;
 
-       if (mask == TRACE_ITER(RECORD_TGID)) {
+       case TRACE_ITER(RECORD_TGID):
 
                if (trace_alloc_tgid_map() < 0) {
                        tr->trace_flags &= ~TRACE_ITER(RECORD_TGID);
@@ -5307,24 +5312,27 @@ int set_tracer_flag(struct trace_array *tr, u64 mask, 
int enabled)
                }
 
                trace_event_enable_tgid_record(enabled);
-       }
+               break;
 
-       if (mask == TRACE_ITER(EVENT_FORK))
+       case TRACE_ITER(EVENT_FORK):
                trace_event_follow_fork(tr, enabled);
+               break;
 
-       if (mask == TRACE_ITER(FUNC_FORK))
+       case TRACE_ITER(FUNC_FORK):
                ftrace_pid_follow_fork(tr, enabled);
+               break;
 
-       if (mask == TRACE_ITER(OVERWRITE)) {
+       case TRACE_ITER(OVERWRITE):
                ring_buffer_change_overwrite(tr->array_buffer.buffer, enabled);
 #ifdef CONFIG_TRACER_MAX_TRACE
                ring_buffer_change_overwrite(tr->max_buffer.buffer, enabled);
 #endif
-       }
+               break;
 
-       if (mask == TRACE_ITER(PRINTK)) {
+       case TRACE_ITER(PRINTK):
                trace_printk_start_stop_comm(enabled);
                trace_printk_control(enabled);
+               break;
        }
 
        return 0;
-- 
2.51.0